Help! -- Fish Are Dying!

Here's the scenario:

Had the following stock in my 38 G aquarium:

10 platties
6 rummy nose tetras
3 pearl gouramis
2 bolivian rams
1 kribensis cichlid
1 rainbow shark

Everything was going well; they'd lived peacefully together for months. Tank had been cycled using media from another well established 2yo tank. On one occasion when I introduced I the Bolivians/Gouramis/Rummys there was an ick outbreak; I treated it with temperature (29-31C for a week) and it eradicated the parasites. All of the fish survived and were healthy for at least 2 months after until this happened:

I added 6 ghost shrimp, 5 ottos, and 3 more rummy nose tetras, ~2wks ago...

I was pretty foolish in doing so because the tank with the rummys had only those 3 left and there was a dead one floating at the back... I know this is far from ideal conditions to be buying fish, but I was fairly desperate and didn't have many other opportunities to get to the LFS, so I reluctantly bought them.

A few days later I noticed that one of my platties had what looked like finrot; it's tail had sort of opaque blotches on it and I wasn't sure how to treat it. It wasn't really shredded. It just sort of looked a bit cloudy (the caudal fin). The next day I noticed some ich on 2 of the rummys. I wasn't sure how to treat the former, but had good results with the temperature ich method. Thus, after 2 days of BIG like 40% water changes I raised the temp slowly to 29C (stops ich reproduction) and then a few days after to 31 (kills ich). Kept it for about a week like that and now bringing it back down to normal (25C). In this time frame though, MANY MANY fish have died. And not from ich (had no symptoms of it). Many just started having what looked like bladder problems, i.e. swimming kind of strangely and floating out of control, or just a lot of resting on the bottom and dying.

The ich went away, but I've lost a platy (found dead on the gravel), have 2 more of them sitting on the bottom or acting strange at the top of the tank, had THREE ottos die (not so surprised as their pretty fragile), had FIVE rummys die, and finally and most crushing of all, my rainbow shark, once such an amazingly hardy fish and 2.5 years old (!!!!) has started floating upside down in his cave.

What is going on!!? Is it the temperature, or the ich, or this disease the platies got upon addition of new fish? What should I do?

Other info:

I started using a differen't dechlorinator/conditioner for the water not too long before this all happened. In fact about a day or two before adding hte new fish. It's a different brand (Big Al's) to what I normally used and I'd had it in my drawer at room temperature for about 6 months before using this. Could this be defective/these be symptoms of chlorine exposure?

Also the fish aren't gasping at the surface so I don't thinkt he high temperature is causing them to have an O2 shortage.

Check the date on the declorinator bottle.
Parasites can cause bacterial infections.
Are you still treating for the whitespot or has it gone now.

I've stopped treating for ich now (it's been 10 days of 31C). There are no whitespots on my fish, but some other symptoms remain that predated the ich:

Another platy died today (found on bottom; had no white spots on it). The cloudy/opaque caudal fin on a platy was the first symptom before the ich outbreak in the rummy noses. I also just got a good look at my rainbowshark with a flashlight. It's very pale and most noticeably it's head has little pinhead sized perferations on it that are kind of a dull grey and bloody or red at their core; if I look into it's gill they are quite red (perhaps they are always like this without me noticing). One more of the platies has a similar head; it looks like it's shedding it's skin or something; it's also missing an upper lip or something.

Any ideas what these are symptoms of?

Can you post your water stats please.
The symtoms you are descibing point to bad water quality, parasites, columnaris.
Is it possible to load a pic up of the shark. On head region does it look like pitting.
Any signs of flicking and rubbing.
Do you mean the mouth rotting away on a fish.

from my basic research it looks like columnaris? do you agree? if so, what's the best treatment method?

Wilder said:

Can you post your water stats please.
The symtoms you are descibing point to bad water quality, parasites, columnaris.
Is it possible to load a pic up of the shark. On head region does it look like pitting.
Any signs of flicking and rubbing.
Do you mean the mouth rotting away on a fish.

Click to expand...

I don't have a test kit unfortunatly. However, I have an understanding of the nitrogen cycle and do regular 25% water changes every 10-14 days, and am very careful to dechlorinate the water and to not kill bacteria in my filter media; this tank has been established for some time now without casualties so i'm certain it's not new tank syndrome. I don't think I was pushing the bioload limit at all and I'm pretty sure this has been the result of one or a combination of pathogens -- perhaps ich (certainly was on tetras) and columnaris or something else. I'd really like to diagnose the latter so I can treat my fish before they all die -- my rainbow shark is my oldest fish i currently have at 2.5 years! would be such a shame to lose it. Also no signs of flicking or rubbing (ie high nitrates)

The platy's mouth appears to have rotted away, yes. Again, as seen in the pics it looks like their heads are perforated and flaky; the platy's eyes look especially strange. I've lost 4 platies total.

If the platy mouth rotted I would end its misery.
Uk for columnaris pimafix and myxazin by waterlife.
United states maracyn one and two.

I couldn't bring myself to kill the platy, but i was worried it could spread some sort of infection, so i removed it from the tank and put it in a large betta bowl with some tank water and gravel and about 50% new freshwater. i figured there i'd be able to observe it and hopefully it'd get better.

amazingly (or perhaps not!) 3 days later she gave birth to 8 fry! i'm so pleased because i've never had any fry survive before in my community tank (i've seen them twice and subsequently get eaten right in front of my eyes). so i'll let them grow for maybe another week or two and then move them into the 10 gallon without the mom. they're a solid week old now i'd say. i have a fry question that may already be answered in other subforums. i'll ask it here as well as it concerns the mother:

should i use aquarium salt to help with the disease? will it help the fry or be harmful to them? also i'm feeding them crushed up flakes and notice they eat it without problem. since the betta bowl isn't filtered i'm doing 50% water changes every other day.

You can use salt with fry.
Hows the fish mouth doing.

Thanks -- did a 50% water change to the small (~2-3 gallon) bowl. I added a small amount of aquarium salt so it wouldn't be too stressful (it's very hard to change; it's too small to gravel clean and so i've been using a turkey baster to remove waste from the gravel fairly unsuccessfully).

I'm hoping the salt also helps the sick platy. I'd say the mouth is better, but the fish is by no means fully recovered. it is a little bit active, but not as much as you'd expect a healthy fish -- however, that being said, in such a confined space it's not much of a surprise. Even though the mouth is better, one eye is still very cloudy and it's skin looks a little flaky. i'm concerned the fry will get sick as well, although i'm thinking that perhaps it'd be too late since their mother was sick while pregnant + they've been with her for a week in close quarters. What would you do? Should I separate them from their mother? I could put them in a separate bowl from her just as a precaution (also I don't think she'd be able to eat them as they're already nearly 1cm long and too alert to be caught).

I can post pics if you think it'd be helpful. Interestingly my rainbow shark is looking and acting a lot better, although he/she still is unusually elusive and doesn't go on little terrorizing runs around the tank. Just stays in its cave, but thankfully not upsidedown anymore. The head has recovered to a more solid, smooth, darker hue which is a sign of progress i'd say. Some of the platies (6 left) in the community tank seem to have slightly opaque blotches on the rims of their caudal and anal fins, but they swim and eat and act as healthy as ever, so i'm not sure if i should be concerned. perhaps if this salt 'bath' helps the sick mother then i'll consider doing the same to the others.

I think I would add a bacterial med to both tanks.
What's your location.
Float a plant at the top of the tank for the fry to hide in.

Are antibiotics safe for fry? Is there a particular brand that I should look for?

I live in Ontario, Canada.

Here are some pics of the sick mom/fry tank.

Maracyn one and two for columnaris to cover all bases.
Not sure if you can use full dose with fry. I know you cant use full dose when using a parasite med.
Or bless her all on her own.
Maybe try half dose and see how the fry go.

Note her eye. Also is that a gravid spot? Is she still pregnant?

Alright I'll see if I can get a hold of those antibiotics